Resolution:
Installing hawk 4.8.0 on top of tra 5.5 breaks the domain with the below error:
===========================================
java.lang.ClassCastException:
java.lang.Long   at
com.tibco.tra.tsm.TSM.onMicroAgentAdded(TSM.java:4056)   at
COM.TIBCO.hawk.agent.macollection.Collection$ContainerEventListenerAdapt
er.onMicroAgentAdded(Collection.java:485)   at
===========================================
The problem is that TSM invokes Hawk HMA getProcess microagent and the
4.8 version of HMA has certain field that is Long, but TSM is still
trying to cast it to Integer.

Trying to downgrade to hawk 4.7.0 by reinstalling hawk 4.7.0 or tra 5.5
failed with the same error.

The workaround is to:
1. make sure there is no hawkagent and tibhawkhma process running.
2. copy the hawkhma.exe from Hawk 4.7 to Hawk 4.8 folder, and then restart TRA Hawkagent.
Or better yet, one can remove the whole hawk 4.8 folder,  replace it with the hawk folder from 4.7.0 and restart TRA HawkAgent.

Another better solution is to install hawk 4.8.1 which will address the issue. Hawk 4.8.1 will be released by the end of July 2008.